Confluent and Reticulated Papillomatosis of Gougerot and Carteaud: A Case Report and Review of the Literature

Confluent and reticulated papillomatosis (CARP) of Gougerot and Carteaud is a rare chronic disease with exacerbation and remissions typically affecting young people. Classic clinical characteristics include asymptomatic scaly hyperpigmented macules, patches, and papules in the trunk's confluent and reticular pattern. A 12-year-old girl, otherwise healthy, presented with itchy, persistent skin lesions all over her body for one year. Skin examination revealed generalized scaly brownish patches, thin papules, and plaques all over her body, including her face, neck, middle of the chest, abdomen, back, upper extremities, elbows, lower extremities, and knees. Wood's lamp examination of her skin lesions was unrevealing. Skin biopsy showed papillomatosis, hyperkeratosis, acanthosis, and hypergranulosis. The dermis showed perivascular inflammatory cellular infiltrate. Based on the above clinicopathological findings, the patient was diagnosed with CARP. In our case, a generalized form was reported. CARP is diagnosed based on clinical and histopathological features. Oral antibiotics are the cornerstone of treatment. Our patient responded well to oral minocycline 85 mg one tablet daily, tacrolimus 0.1% ointment twice daily, and selenium sulfide shampoo twice weekly for two months. The classic clinical characteristics of CARP include asymptomatic scaly hyperpigmented macules, patches, and papules in a confluent and reticular pattern on the trunk. A generalized form, as in our case, has been reported. CARP is diagnosed based on clinical and histopathological features. Oral antibiotics are the cornerstone of treatment.


Introduction
Confluent and reticulated papillomatosis (CARP) of Gougerot and Carteaud is a rare chronic disease, consisting of exacerbations and remissions, and it typically affects young people. It is characterized by asymptomatic scaly, hyperpigmented papules and plaques that are reticulated at the periphery and confluent in the center. A hypopigmented variant of CARP was previously described [1]. This variant typically affects the intermammary region, epigastric area, and upper back, and less commonly, the neck, axillae, shoulders, and face. The precise underlying cause has not been determined yet. Abnormal host reaction to Pityrosporum organisms or bacteria, hyperinsulinemia, insulin resistance, Cushing disease, menstrual irregularities, thyroid disease, pituitary dysfunction, hirsutism or hypertrichosis, obesity, acanthosis nigricans, ultraviolet light exposure, amyloidosis, and the disorder of keratinization with overexpression of keratin-16 have been suggested to play a role in the development of the disease [2]. Pregnant women or individuals who lose weight frequently experience CARP remission. Familial cases of the disease have been reported, but the familial occurrence is typically sporadic. This condition is quite common among adolescents and young adults with blacks suffering from the condition twice as much as whites. According to previous studies, some studies noted a male predominance while others noted a female predominance [2,3]. Treatment of the disease includes topical and systemic treatments. Systemic treatment includes minocycline, doxycycline, antifungals, retinoids (isotretinoin, acitretin), oral contraceptives, and/or phototherapy [2]. Topical treatment includes lactic acid, selenium sulfide shampoo, antifungals, mupirocin, retinoids, salicylic acid, urea, tacrolimus, and/or vitamin D analogs. A case of CARP with a generalized distribution is presented in this case report.

Case Presentation
A 12-year-old girl, otherwise healthy, presented with a new onset of itchy, persistent, and slowly progressing skin lesions over her body for one year. Systemic examinations, past medical history, drug history, and family background were unremarkable. Skin examination revealed generalized scaly brownish patches, thin papules, and plaques covering her body, including her face, neck, middle of the chest, abdomen, back, upper extremities, elbows, lower extremities, and knees (Figures 1-3). Hair, nails, and mucous membrane examinations were normal.   Wood's lamp examination of her skin lesions was unrevealing. Skin biopsy showed papillomatosis, hyperkeratosis, acanthosis, and hypergranulosis. The dermis showed perivascular inflammatory cellular infiltrate ( Figure 4). According to the above clinical and pathological findings, the patient was diagnosed with CARP. She was treated effectively with minocycline, one 85 mg tablet orally for two months, tacrolimus 0.1% ointment twice daily, and selenium sulfide shampoo twice weekly.

Discussion
CARP was described first in 1927 by two French dermatologists, Gougerot and Carteaud [3]. CARP is a rare chronic disease with exacerbations and remissions, typically affecting young people. The unusual features in our case included the generalized appearance of skin lesions and the appearance of well-defined lesions over the elbows and knees resembling type IV pityriasis rubra pilaris (PRP). However, the histopathological features were typical for CARP. The differential diagnosis in our case included PRP, tinea versicolor, keratosis lichenoides chronica, and symmetrica progressiva. The skin lesions of PRP are not reticulated, and the presence of follicular papules is crucial for PRP [4]. Tinea versicolor skin lesions are not reticulated. The skin lesions of keratosis lichenoides chronica are reticulated and occur around the midline of the body, similar to CARP; however, the lesions of CARP are typically lichenoid [5]. The characteristic histopathological features of CARP, which are club-shaped, bulbous epidermal rete ridges with pigment at their bases (dirty feet), were not seen in our case; however, the other histopathological features in our case were typical for CARP. The most effective treatment for CARP is oral antibiotics (minocycline and doxycycline) [2]. CARP responds to treatment but recurs after discontinuation of the treatment. Table  1 represents our literature review of 21 cases with CARP at different lesion sites for which the majority of cases were localized along the trunk. To our knowledge, no case with generalized lesions, including face, neck, middle of the chest, abdomen, back, upper extremities, elbows, lower extremities, and knees, has been published. Our patient responded well to oral minocycline, a dose of one 85 mg tablet daily, tacrolimus 0.1% ointment twice daily, and selenium sulfide shampoo twice weekly for two months.

Case Citation
Year Gender Age Site Treatment Outcome

Conclusions
CARP is a rare condition most often occurring in young adults. Classic clinical characteristics include asymptomatic scaly hyperpigmented macules, patches, and papules in a confluent and reticular pattern on the trunk. A generalized form of CARP, as described in our case, was previously reported. CARP is diagnosed based on clinical and histopathological features. Oral antibiotics are the cornerstone of treatment.

Additional Information Disclosures
Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.